What changes are observed in the uterus if the fertilisation does not occur?

i) The menstruation cycle results when the fertilization of the egg by the sperm does not take place.


ii) The ovaries release an egg every month and hence the walls of the uterus already prepare itself for embedding and nourishing the embryo. This causes the uterine walls to thicken and become spongy.


iii) When the egg does not get fertilized, it remains viable for a day after which it does not survive.


iv) Since the egg does not get embedded in the walls of the uterus, the thick lining is not needed anymore and it sheds off in the form of blood and mucous which comes out of the vagina.


v) This process takes place every month and is known as the menstrual cycle which lasts for about 2-8 days every month.


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